Buggy code:
@ Component public class TransformersHandler { public Map < String , Serializable > runTransformers ( Map < String , Object > rawData , List < Transformer > scopeTransformers ) { Map < String , Serializable > transformedData = new HashMap < > ( ) ; for ( Transformer transformer : scopeTransformers ) { String key = keyToTransform ( transformer ) ; Object value = rawData . get ( key ) ; try { @ SuppressWarnings ( "unchecked" ) Object transformedValue = transformer . transform ( value ) ; transformedData . put ( key , ( ( Serializable ) ( transformedValue ) ) ) ; } catch ( ClassCastException e ) { Class transformerType = getTransformerFromType ( transformer ) ; if ( ( value instanceof Map ) && ( transformerType . equals ( List . class ) ) ) { throw new RuntimeException ( ( ( ( "Under<seq2seq4repair_space>property:<seq2seq4repair_space>'" + key ) + "\'<seq2seq4repair_space>there<seq2seq4repair_space>should<seq2seq4repair_space>be<seq2seq4repair_space>a<seq2seq4repair_space>list<seq2seq4repair_space>of<seq2seq4repair_space>values,<seq2seq4repair_space>but<seq2seq4repair_space>instead<seq2seq4repair_space>there<seq2seq4repair_space>is<seq2seq4repair_space>a<seq2seq4repair_space>map.\n" ) + "By<seq2seq4repair_space>the<seq2seq4repair_space>Yaml<seq2seq4repair_space>spec<seq2seq4repair_space>lists<seq2seq4repair_space>properties<seq2seq4repair_space>are<seq2seq4repair_space>marked<seq2seq4repair_space>with<seq2seq4repair_space>a<seq2seq4repair_space>'-<seq2seq4repair_space>'<seq2seq4repair_space>(dash<seq2seq4repair_space>followed<seq2seq4repair_space>by<seq2seq4repair_space>a<seq2seq4repair_space>space)" ) ) ; } if ( ( value instanceof List ) && ( transformerType . equals ( Map . class ) ) ) { throw new RuntimeException ( ( ( ( "Under<seq2seq4repair_space>property:<seq2seq4repair_space>'" + key ) + "\'<seq2seq4repair_space>there<seq2seq4repair_space>should<seq2seq4repair_space>be<seq2seq4repair_space>a<seq2seq4repair_space>map<seq2seq4repair_space>of<seq2seq4repair_space>values,<seq2seq4repair_space>but<seq2seq4repair_space>instead<seq2seq4repair_space>there<seq2seq4repair_space>is<seq2seq4repair_space>a<seq2seq4repair_space>list.\n" ) + "By<seq2seq4repair_space>the<seq2seq4repair_space>Yaml<seq2seq4repair_space>spec<seq2seq4repair_space>maps<seq2seq4repair_space>properties<seq2seq4repair_space>are<seq2seq4repair_space>NOT<seq2seq4repair_space>marked<seq2seq4repair_space>with<seq2seq4repair_space>a<seq2seq4repair_space>'-<seq2seq4repair_space>'<seq2seq4repair_space>(dash<seq2seq4repair_space>followed<seq2seq4repair_space>by<seq2seq4repair_space>a<seq2seq4repair_space>space)" ) ) ; } <START_BUG> if ( ( value instanceof String ) && ( transformerType . equals ( LinkedHashMap . class ) ) ) { <END_BUG> throw new RuntimeException ( ( ( "Under<seq2seq4repair_space>property:<seq2seq4repair_space>'" + key ) + "'<seq2seq4repair_space>there<seq2seq4repair_space>should<seq2seq4repair_space>be<seq2seq4repair_space>a<seq2seq4repair_space>map<seq2seq4repair_space>of<seq2seq4repair_space>values,<seq2seq4repair_space>but<seq2seq4repair_space>instead<seq2seq4repair_space>there<seq2seq4repair_space>is<seq2seq4repair_space>a<seq2seq4repair_space>string." ) ) ; } if ( ( value instanceof String ) && ( transformerType . equals ( List . class ) ) ) { throw new RuntimeException ( ( ( "Under<seq2seq4repair_space>property:<seq2seq4repair_space>'" + key ) + "'<seq2seq4repair_space>there<seq2seq4repair_space>should<seq2seq4repair_space>be<seq2seq4repair_space>a<seq2seq4repair_space>list<seq2seq4repair_space>of<seq2seq4repair_space>values,<seq2seq4repair_space>but<seq2seq4repair_space>instead<seq2seq4repair_space>there<seq2seq4repair_space>is<seq2seq4repair_space>a<seq2seq4repair_space>string." ) ) ; } String message = ( ( ( ( ( "Data<seq2seq4repair_space>for<seq2seq4repair_space>property:<seq2seq4repair_space>" + key ) + "<seq2seq4repair_space>-><seq2seq4repair_space>" ) + ( rawData . get ( key ) . toString ( ) ) ) + "<seq2seq4repair_space>is<seq2seq4repair_space>illegal." ) + "\n<seq2seq4repair_space>Transformer<seq2seq4repair_space>is:<seq2seq4repair_space>" ) + ( transformer . getClass ( ) . getSimpleName ( ) ) ; throw new RuntimeException ( message , e ) ; } } return transformedData ; } private Class getTransformerFromType ( Transformer transformer ) { } public void validateKeyWords ( String dataLogicalName , Map < String , Object > rawData , List < Transformer > allRelevantTransformers , List < String > additionalValidKeyWords ) { } private String keyToTransform ( Transformer transformer ) { } }

Fix:
if ( ( value instanceof String ) && ( transformerType . equals ( Map . class ) ) ) {